As a general guideline, Doug Sklar, a certified personal trainer and founder of PhilanthroFIT in New York City, recommends ...

Then, elevate the heart rate a bit with a short 3-5 minutes on the rower or treadmill. “After that, you can work planks into the circuit, which will help turn on your midline even more,” he says.

Begin in a forearm plank position with elbows under shoulders, knees off the ground, pelvis tucked and glutes engaged. You can bring feet out a bit wider than hips-distance apart to create strong ...